The present invention relates to temperature sensors, and more particularly, to temperature sensor probes which are releasably attached relative to a wall structure with a thermowell. The present invention relates both to the structure of a thermowell adapter and to the method of attaching the temperature sensors probes relative to a wall structure by using the thermowell adapter.
Numerous temperature sensor structures are known in the prior art, many of which have a temperature sensitive element disposed on the end of a probe. Often it is desired to extend the temperature sensitive element into a fluid flow, such as into the center of an air flow duct, into the center of a liquid flow pipe, into a wind or out from a moving vehicle. The support structure for the temperature sensitive element should disrupt the flow as little as possible, but must be strong enough to withstand the drag of the flow. A metallic sheath is a common component of temperature probes used to support the temperature sensitive element. Sheathed temperature probes commonly include a long, thin cylindrical metallic sheath which houses the temperature sensitive element and extends into the flow. Common sheathed temperature probes include lengths ranging from about 2xc2xd to 12 inches and outer diameters ranging from about xe2x85x9 to xe2x85x9c of an inch.
Often it is desired to attach the temperature probe to a wall or other support structure. With piping and duct systems, it is commonly desired for the temperature probe to attach to the pipe wall or duct wall from outside the pipe or duct. The easiest way to form such an attachment is by opening a hole in the pipe wall or duct wall and inserting one end of the temperature probe through the hole into the pipe or duct. However, any removal or replacement of the temperature probe in such systems opens a leak in the flow piping or duct work. Particularly in fluid systems wherein emptying and filling the system with fluid takes a substantial amount of time, or in systems carrying hazardous fluids, such leaks must be avoided.
Thermowells are structures that are permanently attached into the wall of a pipe or duct. Thermowells extend a recess toward the center of the piping or duct work and into the center of the flow. Thermowells are typically metallic, and the temperature inside the recess is intended to be as close as possible to the temperature of the flow. The temperature probe is inserted into the thermowell, and senses temperature of the flow via conduction through the thermowell. When a thermowell is used, the temperature probe can be removed from the thermowell, and tested, calibrated or replaced, without removal of the thermowell or interruption of the fluid flow.
Commonly, thermowells include internal threading so the temperature probe received therein can screw into the thermowell for attachment. In practice, however, the threaded attachment can be a source of failure for the temperature probe as workers in the field improperly torque the temperature probe into the thermowells. In particular, temperature probes typically include a plurality of wires or leads which extend from the proximal side of the probe. While workers during initial installation will commonly screw the temperature probe into place prior to connecting the leads, the same does not hold true during testing or calibration. If a field worker needs to test the temperature probe in the system but with the temperature probe removed from the thermowell, the field worker may not go to the trouble of disconnecting the leads prior to unscrewing the temperature probe from the thermowell. In addition, the field worker may unadvisedly unscrew the temperature probe without the proper tools, such as by hand rotation of any flange on the temperature probe. This unadvised removal process may stress and break the leads or otherwise damage the temperature probe.
The present invention is a thermowell adapter, which permits installation and removal of a temperature probe into a threaded thermowell without screwing of the temperature probe. The thermowell adapter has a head and a body extending from the head, which jointly define a passageway. The body of the thermowell adapter has external threading for receipt in the internally threaded thermowell. A temperature probe is received into the passageway such that a sensing element of the temperature probe extends into the thermowell. An axial securement on the head releasably prevents the temperature probe from moving axially in the passageway. Separate from the axial securement, a rotational securement prevents the temperature probe from rotating about its axis in the passageway.